This invention relates to absorption refrigeration systems and more particularly to an improved purge arrangement for removing noncondensible gases or vapors fron an absorption refrigeration system employing an additive, such as octyl alcohol, in the system.
Various types of refrigeration systems, and particularly absorption refrigeration systems using lithium bromide solution for absorption of refrigerant vapor, require noncondensible gases be removed from the absorber region of the system to maintain its operating efficiency, since the presence of noncondensible gases, even in small quantities, seriously reduce refrigeration capacity by tending to blanket the absorber solution and substantially reduce the quantity of refrigerant vapor which is absorbed, causing the pressure in the absorber, and hence in the evaporator, to rise with consequent reduction of evaporation of refrigerant and cooling capacity. Purge arrangements for removing noncondensible gases from absorption refrigeration systems are known to the art, the simplest and least expensive arrangements employing a vacuum pump to expel these gases from the system.
It is common practice in the art of absorption refrigeration to add a quantity of octyl alcohol (2-ethyl-n-hexanol) to an absorption refrigeration system to improve the performance of the absorber and condenser and to thereby substantially increase the over-all capacity of the system. However, octyl alcohol is volatile and exists partially in a gaseous state in the absorber. Accordingly, it is possible for the octyl alcohol gas to be removed from the system by the purge pump, with consequent loss of capacity of the system. Also, it is possible to lose refrigeration capacity because of the tendency of the alcohol to settle out in certain locations in the absorption system it is not circulated with the absorbent or refrigerant and where it is apparently inhibited from entering into the gaseous phase, due to the limited solubility of the octyl alcohol in both the refrigerant (water) and in the aqueous lithium, bromide solution. Accordingly, the alcohol exists in a partially undissolved liquid phase in the system and, because its specific gravity is less than that of either water or the solution, the alcohol floats on the surface of these liquids and accumulates in sumps or other portions of the system where its usefulness is diminished.
The present invention is directed to, and has for its principal object, an improved purge arrangement for absorption refrigeration systems including means for purging noncondensible gases from the system while maintaining the presence of octyl alcohol in the system. In describing the system, reference will be made herein to a typical absorption refrigeration machine in which the generator and condenser are arranged in one shell, and the evaporator and absorber are arranged in another shell. It is obvious, however, that absorption refrigeration machines may take many other forms and the description should not necessarily be restricted to the particular arrangement described. Also, while the specification refers to an absorption refrigeration system of the type using lithium bromide as the absorbent solution, many other absorbent-refrigerant combinations are known; and it is not intended that the invention be limited to this particular system.
Other objects and advantages of the invention will be apparent from the following detailed description of a preferred embodiment thereof when taken in conjunction with the drawings.